I have a MPB running Mavericks (as per sig). Recently, I've tried connecting 2 different external display's to the MBP via an Apple Thunderbolt to VGA adaptor. I can't get the resolution of the connected displays to go above 800 x 600, and it looks awful.

The first screen is a Samsung SyncMaster T260HD with a native res of 1920 x 1200, and the other is a Samsung SyncMaster 933HD, with a native res of 1366 x 768. I plug them into my Windows box (also as per sig) via a VGA cable (with a DVI to VGA adaptor), and it will drive each display at it's native res just fine. So what have I missed to get the MBP to do this???

Yes, I know VGA isn't optimal, but it's the only Apple adaptor I have lying around and should work either way!